Brain Injury May Occur at Impact of Auto Accident

New research shows that brain injury may occur within one millisecond after a human head is thrust into a windshield as a result of a car accident.

Researchers at the U.S. Sandia National Laboratories (Albuquerque, NM, USA) and the University of New Mexico Health Sciences Center (Albuquerque, NM, USA) made the discovery after modeling early-time wave interactions in the human head following impact with a windshield, a scenario that could lead to traumatic brain injury (TBI). The injury occurs prior to any overall motion of the head following impact.

The researchers imported a digitally processed, computed tomography (CT) scan of a healthy female head into the Sandia-developed shock physics computer code. The CT scan was digitally processed into a computer model that segmented all soft tissue and bone into three distinct materials: skull, brain, and cerebral spinal fluid (CSF). Computer models were then constructed representing the skull, brain, CSF, and windshield glass, and simulations were run that represented what would happen to an unrestrained person hitting the windshield of an automobile in a 55 km/h head-on collision with a stationary barrier.

It became apparent that different types of cell damage might occur depending on the type of stress to which the cells are exposed. Isotropic stress--commonly called pressure stress--imposes density changes that can damage a cell's internal structure. Shearing stress acts as a tearing mechanism that damages the cell wall and membranes, giving rise to apoptosis, or cell death. Both are likely at play in most incidents leading to TBI.

"In the past not a lot of attention was paid to modeling early-time events during TBI,” said co-author engineer Paul Taylor of Sandia's multiscale computational materials methods department. "People would--for example--be in a car accident where they hit their head on a windshield, feel rattled, go to an emergency room, and then be released. We were interested in why people with head injuries of similar severity often have very different outcomes in memory function or returning to work.”



Related Links:
Sandia National Laboratories
University of New Mexico Health Sciences Center